Sited under a landscaped area, the attenuation tank is designed to alleviate flood risks and to cater for a 1 in 100-year storm surge event on the St John’s Mews development of 111 prestigious properties.
The tank is amongst a number of precast concrete types that are now accepted by Yorkshire Water within Sewers for Adoption 6th and 7th Editions and is part of the FP McCann StormStore™ tank and chamber range, which can be designed and installed up to 6 metres high with overall dimensions to suit the client brief.
Measuring 11 metres long by 8 metres wide and 1.2 metres high, the Wakefield StormTank™ manages a storm event by capturing excess surface rain water. The water can then be released back into the drainage system at a controlled rate, thereby relieving the pressure on the main drainage network and reducing the risk of downstream flooding.
Prior to the construction of the tank, a 75mm thick blinding layer of stone and concrete was formed to receive the foundation floor, a 300mm thick C40 concrete steel mesh reinforced slab. The panel sections were manufactured at FP McCann’s state-of-the-art precast facility in Byley, Cheshire and delivered to site over a period of one week for installation by the approved FP McCann specialist fixing team.
In total, ten external walling units were fixed and four special internal support walls were fixed, creating three lanes within the tank. Large openings in the internal walls allow water to flow freely between each section. Covering the tank are five individual cover slabs, each weighing 11 tonnes. Three clear manhole openings have been cast into each of the end slabs to give easy access for maintenance purposes. The tank has been set on a 1:400 fall towards the outlet and the base is complete with a dry weather flow channel.
The off-line panel tank is connected to the end of a 600mm diameter precast concrete pipe storage system to provide the additional overflow capacity on the development.
Commenting on the StormTank™ design and build, David Stafford Managing Director of Connaught says, “Mindful of the precast options available and their adoption via Yorkshire Water’s stringent S104 approval process, FP McCann’s multipurpose panel tank design was our choice of attenuation system. The FP McCann approved installation team undertook the work in a timely, efficient and safe manner. We will certainly consider similar FP McCann supply and install precast concrete panel tanks systems on future housing projects.”
FP McCann’s StormTank™ has a design life of 100 years, has no footprint size limitation and is designed for pedestrian loading through to LM1 highway loading. Internal design features can be added such as weir and baffle walls and penstocks or flap-valves can be pre-installed.
Typical uses include:-
- Attenuation Tank
- StormBrake™ Chambers
- Pumping Stations
- Large CSO Chambers
- ASP Structures
- Clean Water Storage Tanks